Finned tube



y June-3, 1930.

H. W. BUNDY Filed July 5, 1927 hmmm A A TTORNE Y.

Q\ J 1 www1 uw .LM 1MM Q 1 Patented June 3, 1930 UNITED STATES PATENT?` OFFICE HARRY W'. .BUNDY,' OF DETROIT, .MICHIGAIL ASSIGNOR, BY MESNE ASSIGNMENTS, T0 BUNDY TUBING COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN FINN ED TUBE Application led July 5, 1927. Serial No. 203,383.

This invention relates Ato a finned tube. Finned tubing of the type referred to 1s useful for the transference of heat, as for'` example in automobile radiators, mechamcal refrigerating devices and the l1k e. ,Tubing which includes a tubular body w1th separate fins secured to the outside of the tubular body in one way or another has been proposed heretofore. The present invention contemplates a tube wherein the body of the tube and the' l fins' are integral. Such a tube is advantav tube.

geous in that an efficient transference of heat is effected by conduction from the body of the tube to the fins, whereas, in the type of tube usin separate fins there is more or less of a brea between the body of the tube at the point where the fins are secured to the tube. yBy making the body of the tube and the fins integral and of a single piece of metal there is no connection. between the tube and the lins which would interfere with the conduction of heat. Moreover, the fins are not liable to become vloose from the tubular body; this makes the tube less delicate so that it is easier to handle during manufacture and shippage, and the like, and gives the tube a longer life. The method by which this tube is made is described and claimed in my copending application, Serial No. 203,381, filed July 5, 1927.

In the accompanying drawings:

Fig. 1 is an assembly view showing diagrammatically the manner in which the tube can be made. Y

Fig. 2 shows in section a battery of rolls for forming pleats or folds in the stock which eventually becomes lins on the completed taken through such tube Fig. 8 is a side view of a portion of a tube showing a further modified form.

ig. 9 is a sectional view taken through the tube shown in Fig. 8. v

Figs. 10 to 13 inclusive are views showing rollers for forming pleats or folds in the stock which eventually become the fins on the tube, in a manner different from that shown by the rolls of Fig. 2.

Inasmuch as the tube itself is claimed in this application, the method of making the tube is not gone into with 4the detail of the above mentioned' copendin application which claims the method. owever, it is thought advantageous in order to clearly describe the nature of the tube to cover in a general manner how it is made. A supply of strip stock in a roll is shown at 1, and the strip stock is drawn through an acid bath 2. It is then drawn over a guide roller 3 andy through a battery of rollers A. for formin pleats or folds in the stock. This battery o rollers is best shown in Fi 2. The first pair of rollers 5 are provide with a cooperating groove and rib which form a fold in the metal and thus narrows the stock in width. The succeeding rolls 6, 7 and 8 have more cooperating grooves and ribs, and each set pf rollers adds one fold or pleat in the stoc The stock thus formed with the pleats is then drawn through a battery of rollers and dies B. Fig. 3 shows these rollers arranged in proper sequence. By inspection of Fig. 3 it will be seen how these rollers progressively act upon the stock as the stock is drawn through the rollers to roll the stock into a tube. In the form shown, a double wall tube is provided. Note that an excess of stock is left at one side of the pleats, and this is first rolled into tube form, and then the portion of the stock provided with the pleats is rolled around the tube formed by this first mentioned portion of the stock. Forming rollers of the type shown in Fig. 2 and Fig. 3 are well known to those versed in the art as is theirA operation of grooving or shaping of stock. In my Patent N o. 1,476,7 96, granted December 11, 1923, I described and claimed the mechanism which includes rollers for through a heating die I Any number of fins can ing of a tube vand the fins and gives the iin a making a double wall tube, and these rollers are quite similar to those shown in Fig. 2 herein. Between each set of rollers in the battery B is preferably placed a die l1 shaped for receiving and guiding the stock as it was formed by the rollers immediately in the rear of the die. These dies are preferably arranged to gradually squeeze the 'folds or pleats formed by the rollers in the battery A so that when the tube is i-n its completed form, as shown at the left hand side of Fig. 3, the folds or pleats are squeezed tightly together. This is clearly brought out in Figs. 5, 7 and With the tube thus formed it is moved forward with continuous longitudinal movement 15 heated by a suitable burner 16. The strip stock, it will be understood, was originally tinned; that is, it may have been tinned before being placed in the supply roll 1, or for that matter, it may be tinned at a point between the supply roller and the battery of rollers A. At any rate, the formed tube is heated in the die so that the coating of solder is made molten and all parts of the tube and the folds or fins sweated together.

This completes the tube but it is preferably drawn through another die 17 which aids in giving the proper final shaped tube. Following this, the tube may be given a solder bath, as at 18, and then cooled by a water bath 19. lfit is desirable to have the ns on the tube in spiral form, the ftube `may be drawn through a die 20 which is arranged to give the tube a twist as it is moved longitudinally through the die. This twists the tube spiral form, as shown in Fig. 4. Following this, lthe tube may be cut oif in suitable lengths by either a hand operated or automatic device 21.

A tube formed as above described is shown at C in Figs. 4 and 5. Note that the inner wall of the tube forms a smooth interior andl that the outer wall of the tube is provided with integral fins D. Both walls of the tube and both parts of the pleat formingy vthe same are securely soldered together. Figs. 6 and 7 show a similar tube E with ve ns F thereon. This is accomplished by adding another pair of rollers to the battery A to place five pleats in the stock.

Figs. 8 and 9 show a tube G with six fins H. be provided to meet the use to which the tube is to be put, and moreover, a tube with any number of fins may be twisted or may be left straight. The battery of rollers A formsthe pleats in the stock by narrowing the stock. This does not stretch or draw the metal, but makes necessary the use of stock originallywider than is necessary to form the tube. The makin this manner is advantageous when very thin stock is used which will not permit of stretching or drawing. However,

'and the pleats can Figs. 10 and 1 3 inclusive, I have shown.

lea-t forming rollers of a different character.

ollers 25 in Fig. 10 have relatively shallow cooperating grooves and ribs which form shallow pleats in the stock by stretching or drawing the metal.v The rollepsZG in Fig. 11 sli htly increase the depth of the pleats; the rol ers 27 in Fig.` 1 further increase the depth of the pleats, and the rollers 28 in Fig. 13 complete the pleats. pleats the width of the stock is not reduced this manner where the stock is of suiiicient 9. thickness to permit stretching or drawing without causing substantial weakening of the stock. The rollers shown in Figs. 10 to 13 form four pleats in the stock for providing a tube with four fins, but it will be understood that smaller or a greater number of pleats may be formed by the use of rollers of the same type. After a tube is formed with the pleats by rollers, as shown in Figs. 10 to 13, the rest of the method is carried out in the same manner as above described.

Claims:

1. A finned tube comprising a relatively long and narrow strip of metal fashioned into hollow cross. sectional form with the lengthwise dimension of the-strip extending lengthwise of the hollow form, a plurality of folds in the strip extending lengthwise -of the same, said folds being entirely outside of the hollow cross sectional form to form exterior lins with theinterior of the hol- By thus forming the be formed in the metal in on the low form substantially unobstructed, said strip with its folds thereon being twisted substantially on the axis'of the hollow cross sectional form whereby the said exterior fins are spiral.

2. A tube comprising an inner tubular ply, an outer tubular ply integral with the inner ply, with both plies comprising a single piece of material and rectly'in the metal of the outer ply.

3. A tube comprising an inner tubular ply of metal, an outer ply integral with the innery ply, and ins formed by longitudinal folds in the metal Aforming the outer ply of the tube. f

4. A tube comprising a body which is formed by a strip of metal rolled transversely to `form a double ply tube, the inner ply of the tube being smoot tube being formed with lone lor more longitudinally extendin folds which form one or more' fins on the tu e.

5,'A tube comprising a formed by a strip of metal rolled transversely to form a double ply tube, the inner ply of the tube being smooth, the outer.' ply of the tube being formed with one or'more longitudinally extending folds which form one or more fins on the tube, the said inner and outer lies and the portions mg soldered together. l

6. A tube comprising a body which is fins on the tube formed dilll body which isA forming each fold. be-

lns

of the tube being smooth, the tube being formed with one outer ply of the or more longitudinally extending folds which form one or more fins on the tube, the said inner and outer plies and the portions forming each fold be.

ing secured together,

and the said tubing being twisted -to give the fins spiral form.

In testimony whereof I ax HARRY my signature. W. BUN DY. 

